Porous web treating apparatus



Sept. 5, 1950 G. D. KNIGHT ETAL POROUS WEB TREATiNG APPARATUS Filed March 27, 1948 IN V EN TORS ATTORNEYS.

Patented Sept. 5, 1950 UNITED STATES, PATENT OFFICE POROUS WEB TREATING APPARATUS Application March 27, 1948, Serial No. 17,434

4 Claims. (Cl. 91-43) The present invention relates generally to improvements in the art of treating sheet material, but relates more specifically to improved apparatus for applying surface coatings or otherwise surface treating various kinds of materials having a relatively porous or permeable nature.

The primary object of our invention is to provide highly efficient apparatus for surface treating porous materials, such as an advancing continuous web of paper stock or the like.

Surface coating and impregnation has long been practiced in many different industries, and especially in the paper making and textile manufacturing industries wherein numerous methods and varied types of equipment have heretofore been proposed and utilized for the purpose of continuously treating sheets, webs, or ribbons of paper and cloth. In order to most effectively coat paper for printing purposes, it is necessary to provide flexible, smooth and relatively soft coatings uniformly and permanently applied to either one or both sides of the sheets with the assistance or aid of simple and dependable apparatus adapted to function at high speed, and none of the prior coating systems meet all of these primary requirements.

Most of the paper coating methods or processes now in vogue, not only necessitate the use of relatively complicated and unreliable equipment usually associated with the paper making machines, but some of them result in the production of hard coatings which have been so compacted by the calender rolls that receptivity to printer's ink has been materially impaired. while others produce spotty coatings which have not been properly anchored to the web and tend to pickoff on the printing presses under the influence of tacky inks. Although some of the prior coated papers have and are being successfully printed with proper and extreme caution on the part of the pressmen, they are expensive to manufacture and result in considerable waste of stock, and improved qualities of cheaper coated printing papers are greatly in demand.

It is therefore a more specific object of our present invention to provide improved apparatus for surface coating porous sheets of paper or the like, on both sides and at minimum cost, with uniform and smooth coatings which will permanently adhere to the materials to which they have been applied.

Another specific object of the invention is to provide simplified and more eificient apparatus for uniformly coating paper webs or the like on opposite sides thereof and immediately following production thereof, in a rapid and most reliable manner, with minimum attention and human effort.

A further more general object of this invention is to provide improved paper treating or impregnating apparatus involving a highly effective principle of uniform application of fluent treating substances, and which may be utilized for efficient application of various types of treating fluids to the opposite surfaces of continuous relatively thin ribbons of stock advancing at high speed.

Still another important object of our invention is to provide an automatic coating or impregnating system for travelling webs of porous material, wherein the treating substances are most effectively anchored to the opposite surface areas of the material with the aid of suction or a vacuum applied in a manner whereby any desired degree of penetration of the web by the substance is obtainable while objectional air is in fact removed from the vicinity of the treated areas.

An additional important object of the present invention is to provide improved porous material treating apparatus which is extremely flexible in its adaptations for the purpose of coating, impregnating or saturating diverse porous materials with diiferent substances so as to meet various requirements.

Another more specific object of the invention is to provide simple and effective instrumentalities. for efiectively treating the opposite sides of a porous rapidly advancing web in an expeditious and automatic manner.

A further object of this invention is to provide compact coating apparatus for uniformly treating both sides of a continuous advancing web of paper, cloth, or the like having relatively porous or fibrous nature.

Still another specific object of our invention is to provide durable and reliable equipment cooperable directly with standard paper making machines of various types, for rapidly and effectively coating the products of such machines with minimum attention and at moderate cost.

The above and other objects and advantages obtainable with the aid of the present improvement, will be apparent from the following detailed description; and the present application is a continuation in part of our Patent No. 2,471,330, granted May 24, 1949.

A clear conception of the features constituting the present invention, and of the construction and operation of typical paper coating apparatus embodying said features, may be had by referring to the drawing accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the various views.

Fig. 1 is an exploded perspective view of a typical vacuum treating unit adapted to apply fluent coating substances to one side of diverse porous or fibrous materials such as paper sheets or cloth;

Fig. 2 is a transverse'vertical section taken through the medial portion of a downward feed coater assembled from parts such as shown in Fig. 1;

Fig. 3 is a transverse vertical section taken through the medial portion of an upward feed coater assembled from parts such as shown in Fig. 1;

Fig. 4 is a diagram of a typical paper coating system embodying coating units such as shown in Figs. 2 and 3 and adapted to coat both surfaces of a continuously travelling paper web; and I Fig. 5 is a transverse section through the medial portion of a slightly modified coater.

While the invention has been shown and de- 7 scribed as being especially advantageously applicable for the specific purpose of coating paper sheets, it is not our desire or intent to unnecessarily limit the scope or the utility of the improved apparatus for use in coating, impregnating,

saturating or otherwise treating other materials having a relatively porous or fibrous nature; and some of the novel features of the web treating method and apparatus disclosed but not specifically claimed herein form the subject of our original application hereinabove identified.

In accordance with our improved process of coating or otherwise treating the surfaces of materials having relatively porous texture, as covered by our prior patent, we create a vacuous condition adjacent to the surface area which is to be coated and apply fluent coating substances under pressure to th surface area in question in close proximity to and laterally of the vacuum zone so that air withdrawn from within and along the surface of, the porous material, will be replaced by treating substance which also spreads over and into the evacuated surface region to produce a zone of impregnation or saturation and a coating firmly anchored to the material. In order to uniformly treat relatively extended surface areas, the vacuum should preferably be maintained of constant intensity, and the vacuous zone and the material may be moved or shifted relative to each other; and when this method is applied to sheets or webs of the material, the vacuum and coating applying zones may be maintained in fixed position and caused to coact with th constantly advancing or travelling webs, and the latter may be coated either on one side only, or on both of the opposite sides thereof in accordance withour present invention. When treating relatively thin sheets or webs, it is necessary to provide a non-porous or impervious backing surface coacting with the web along the surface thereof opposite to the treating zone; and when the opposite surfaces of suchthin sheets are treated in succession, the previously treated areas may be utilized as impervious backings for the areas which are subsequently treated. The several steps of this method of treating may be automatically and continuously exploited or carried on with the aid of relatively simple apparatus, typical embodiments of which are shown more or less diagrammatically in the accompanying drawing.

Referring to Figs. 1 to 4 inclusive of the drawing, the typical paper web coating or treating system and apparatus shown therein by way of illustration, comprises in general two reversely disposable vacuum actuated coaters or treating units 1, 8 cooperable with the opposite surfaces of a constantly advancing porous'paper web I which coacts with reversely revolving main mils III, II respectively and with a series of auxiliary guide rollers I! which are preferably adjustable so as to vary the duration of contact between the web and the main rolls Ni, ii. The unit 1, I

. may be of generally similar construction, each consisting primarily of a series of elongated elements or bars I4, l5, l6 and a pair of spacer blocks ll of suitable thickness,.these bars and blocks being provided with alineable holes ll, i8 for the reception of clamping bolts II for holding the elements in assembled condition. Each end bar it is provided with a series of through openings 2| and with an evacuating manifold 22 communicating with all of the openings 2| and having a central outlet 23 adapted to be connected to a vacuum pump or other locality of reduced pressure, and the bar H of each unit 1, 8 coacts with one side of the intermediate bar I5 which is provided with a cut-out 24 in open communication with the openings 2i and which forms a suction or vacuum chamber or nozzle 25 exposed to the adjacent surface of the advancing web 9.

The opposite face of the medial bar ii of each unit 1, 8, coacts with the adjacent sides of the spacer blocks I! and the opposite sides of these blocks coact with the other end bar I which is likewise provided with a cut-out 26 cooperating with the space'created by the blocks I! to produce a treating substance supply chamber or receptacle 21 of considerable capacity also exposed at its smaller end, to the surface of the advancing web'9 in close proximity to but laterally of the adjacent suction nozzle 25, while its larger opposite end is exposed to atmospheric pressure. In order to permit convenient variation in the thickness of the coating, the holes IS in the bar i6 may be elongated as shown in Fig. 1, thus providing simple means for effecting adjustment of this bar toward and away from the web 9. When the unit I is disposed above the web 9 for downward feed, the receptacle 2! may be directly supplied with an abundance of fluent treating substance containing starch, glue, dye, clay or other suitable ingredients, from above and from any convenient source, as indicated in Fig. 2; and in cases where the unit 8 is located below the web 9 for upward feed, the receptacle 2] may be likewise supplied with an abundance of similar coating substance from below, with the aid of a supply reservoir 28 and a feed pipe 29 communicating with the lower extremity of the chamber 21.

The main rollers ill, Ii preferably andin certain cases necessarily, have non-porous or impervious peripheral surfaces contacting the web 9, and these rollers may also be heated in order to effect drying of the web asit travels in contact with the roller peripheries. The web 9 may be subjected to continuous treating while being delivered from the web forming equipment of the paper making machine, and may be delivered from the roller Ii to the calender rolls or other finishing equipment, in a well known manner. It should be apparent that the coating or treating unit 1 coacts with the roller Hi to continuously coat the upper Surface of the rapidly advancing web 9, while the inverted coatin unit 8 coacts with the roller II to likewise continuously coat the opposite or lower surface of the same web. It

is also to be noted that the coaters or units 1, 8 preferably cooperate with the rollers "I, II to apply the coatings by subjecting the web 9 to vacuum or suction in advance of the zones of application of the coating or treating substance; and in certain cases where maximum vacuum action is desirable, an additional vacuum nozzle or slot may be provided in the manifold 22', in advance of the bar It as shown in Fig. 5, rather than to increase the width of the nozzle 25, so as to prevent the web from being pulled away from its backing roll. The units 1, 8 should rather snugly engage the surfaces of the web 9, and should also be of suflicient length to completely span this web, and the plate l6 should also be adjustable in order to vary the coating thickness.

During normal operation of the typical porous paper web coating equipment, the outlets 23 which communicate with the suction nozzles 25 and with the auxiliary nozzles of Fig. 5 if utilized,

should be connected to a suitable source of vacuum, and the chambers 21 should be constantly supplied with an abundance of suitable coating substance. travels between the coating units 1, 8 and the adjacent rollers If], H, the nozzles 25 withdraw air from within the advancing adjacent zones and these evacuated zones partially fill up with coating substance from the laterally adjacent chambers 21 thereby also depositing a film of coating substance upon the adjacent external surfaces of the web 9. The impervious backings afforded by the rollers I9, ll however prevent air from being drawn directly through the relatively thin web 9 and also prevent the coating solution or treating substance from passing entirely through this web; and when the coated areas have been levelled and have passed beyond their respective units 1, 8, the heated rollers ID, H quickly dry the coatings sufficiently to insure permanent application and setting of the treating substance. The coatings are thus interlocked with the porous or fibrous constituents of the web, and may be effectively finally smoothed and finished by calendering or otherwise.

From the foregoing detailed description of a typical embodiment of the improvement as specifically applied to the treatment of paper, it should be apparent that our present invention provides improved apparatus for coating any material having a porous nature adjacent to the opposite surfaces to which the coatings are applied, with coatings which are firmly anchored to the bodies of the material, The improved apparatus merely involves the creation of a vacuous condition or suction at the surface areas which are to be coated, and the application of fluent coating substance to the surfaces of the material laterally adjacent to the evacuated zones and in close proximity thereto. The coatings thus applied are uniformly thick and smooth, and may obviously be applied either by maintaining the coating units in fixed position while moving the material relative to the stationary applicators, or by moving the coating units along the coat receiving material, or by relatively moving both the coating units and the material.

In cases where the material which is to be coated consists of a relatively thin sheet or web, it is necessary to provide the opposite side with a non-porous or impervious backing; but after a As the porous web 9 subsequently when coating the opposite side.

coating has been applied to oneside of the sheet, the pro-coated side may be utilized as a backing Coating with our improved apparatus may be effected when the material receiving the coat is travelling at relatively high speed as in the case of advancing webs produced in paper making machines, and the characteristics of the coatings may be readily varied by changing the composition of the coating media, by increasing or reducing the injection pressure by varying the vacuum, by altering the duration of contact of the web with the rolls III, II, and by adjusting the bars Hi toward or away from the web 9. The improved method thus becomes highly flexible in its adaptations for diverse treating purposes other than mere coating, and is especially useful in the arts of paper and textile manufacture.

The improved apparatus or units I, 8 for effecting exploitation of our treating process, are obviously simple, compact and durable in construction, and may be readily assembled and dismantled for inspection and cleaning. These treating units may be conveniently installed with comparatively minor alterations in connection with standard paper making and cloth treating machines, to automatically and effectively coat, impregnate, saturate, or otherwise treat both sides of rapidly travelling continuous webs or ribbons of material, with fluent substances comprising various materials and to various predetermined thicknesses. The degree of vacuum, the gaps between the web and the bars l6, and the distribution of the evacuated area may also be varied, in order to vary the injection pressure and thereby the depth of penetration, and the invention has proven highly satisfactory especially for the purpose of coating paper webs in the production of coated paper for printing purposes.

It should'be understood that it is not desired to limit this invention to the precise construction of the apparatus, herein shown and described, for various modifications within the scope of the appended claims may occur to persons familiar with the art; and it is also contemplated that specific descriptive terms used .herein be given the broadest possible interpretation consistent with the disclosure, and that terms such as coating or treating should be considered as having synonymous meaning.

We claim:

1. Apparatus for treating a porous web, comprising, an impervious backing for one side of the web, means for initially evacuating fluid ingredients from a region at and within the surface of the web directly opposed to said backing, means for thereafter separately applying fluent treating substance to the evacuated region opposite to said backing under at least atmospheric pressure and before direct exposure of the region to the ambient atmosphere, and means for relatively moving said backing and said evacuation and substance applying means to advance the web and to thereby enlarge the treated area.

2. Apparatus for treating a porous web, comprising, an impervious backing for one side of the web, means for initially evacuating fluid ingredients from a region at and within the surface of the web directly opposed to said backing, means forming a zone for thereafter separately applying fluent treating substance to the evacuated region opposed to said backing under at least atmospheric pressure and before direct exposure of the region to the ambient atmosphere, means for leveling the applied substance while 1 delivering the treated region to the ambient atmosphere, and means for relatively moving said backing and said evacuation and substance applying means to advance the web and to thereby enlarge the treated area.

3. Apparatus for treating a porous web, comprising, an independent impervious backing for each of the opposite sides of the web, means for initially successively and independently evacuating fluid ingredients from a region at and within a surface of the web opposite to each of said backings, means for thereafter separately applying fluent treating substance to each evacuated region opposite to said backing under at least atmospheric pressure and before direct exposure of the region to the ambient atmosphere, and means for relatively moving said and said evacuation and substance applying means to advance the web and to thereby enlarge the treated areas on the opposite sides oi the web.

4. Apparatus for treating a porous web, comprising, a roll forming an impervious backing for one side of the web, an elongated suction nozzle for initially evacuating fluid ingredients from successive regions spanning the side of the web 8 directly opposite to that contacting said roll, a similarly elongated receptacle segregated from said nozzle by a web engaging wall for thereafter separately applying fluent treating substance to the successive evacuated regions under at least atmospheric pressure and before direct exposure of each region to the ambient atmosphere, and means for rotating said roll to constantly advance the web past said nozzle and said receptacle in succession and to thereby enlarge the treated area.

GEORGE D. KNIGHT. BEN W. ROWLAND.

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS Number Name Date 2,051,201 Davidson Aug. 18, 1936 2,324,787 Lundgreen July 20, 1943 2,354,033 McGladery et a1. July 18, 1944 2,471,330 Knight et al May 24, 1949 

